The present invention relates to a time-setting device for a timepiece, this device including a time-setting stem capable, via a crown topping one of its ends, of being set in a first neutral pushed in position or in at least a second pulled out position for which the stem co-operates with a motion work comprising a wheel and a pinion to allow time-setting of the hour and minute hands.
Such an arrangement has been proposed numerous times. The most common form uses a sliding pinion capable of meshing, via a lever and pull-out piece mechanism, onto an intermediate wheel meshed with a minute wheel. This arrangement, although widely used, is relatively complex and expensive and requires a large number of parts.
One has sought to simplify this time-setting system by reducing the number of necessary parts. For example, the document EP-B-0 261 243 (=U.S. Pat. No. 4,862,434) discloses a time-setting device using not a sliding pinion but a fixed pinion, said pinion having nonetheless a contrate toothing directly meshing with the motion work wheel. Driving of this pinion by the stem is achieved in the following manner: the stem passes through the pinion. It has a first circular cross-section of slightly smaller dimension than the bore of the pinion, so that the stem rotates freely in the pinion when it is in the pushed in neutral position. The same stem also has a second circular cross-section, following the first, of slightly larger dimension than the bore of the pinion, this second cross-section wedging itself in said bore when the stem is in the pulled out position. In this pulled out position, the stem thus drives the pinion, then the motion work wheel and finally the hands of the timepiece for time-setting.